Conventionally, a solid-state image sensor such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device) is widely used for a digital still camera, a digital video camera, or the like.
For example, incident light incident on a CMOS image sensor is subjected to photoelectric conversion in a PD (Photodiode) included in a pixel. Also, electric charges generated in the PD are transferred to an FD (Floating Diffusion) via a transfer transistor, converted into a pixel signal having a level corresponding to a light reception amount, and read.
Further, in recent years, a pixel size has been reduced with miniaturization of a solid-state image sensor, and technology for obtaining sufficient characteristics even in a minute pixel has been developed. For example, the applicant of the present application suggests technology capable of suppressing a variation of a saturation signal amount in a back side illumination type CMOS image sensor (see Patent Literature 1).